An RW offset setting method which includes recording a test pattern by a write head, reading the test pattern by a read head, measuring an amplitude of a read back signal at each tracking position, finding an approximate expression of a profile of the measured amplitude, finding a tracking position, and finding a RW offset based on this tracking position, setting a RW offset for all tracks in the disk device based on the RW offsets about the plurality of tracks to be measured. A read data error recovery method that includes the steps of determining an off-track direction where the amplitude increases, searching an off-track position where the amplitude becomes a local maximum, measuring the amplitude at each off-track position reading data recorded in the data sector.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A RW offset setting method for setting RW offsets which occur between a write head and a read head in a disk device including a rotary actuator having both heads for accessing a disk recording medium, said RW offset setting method comprising the steps of: A recording a test pattern by said write head in each of a plurality of tracks to be measured, which is selected from among a plurality of tracks in said disk recording medium; B reading said test patterns by said read head at a plurality of different tracking positions for each of the plurality of tracks to be measured, and measuring an amplitude of a read back signal at each tracking position; C finding an approximate expression of a profile of the measured amplitude at each of said plurality of tracking positions for each of said plurality of tracks to be measured; D finding a tracking position that gives a maximum value of said approximate expression, of each of said plurality of tracks to be measured; and E based upon the tracking position found for each measured track, determining a plurality of coefficients of a track-dependent arithmetic expression by which a RW offset for a track in said disk device can be calculated.
2. The RW offset setting method; according to claim 1 , wherein said track-dependent arithmetic equation is of order n, where n is an integer greater than or equal to 2, and said method further comprises: setting said plurality of coefficients in said disk device.
3. The RW offset setting method according to claim 1 , wherein said step A , further comprises: recording said test patterns in all data sectors in said plurality of tracks to be measured.
4. The RW offset setting method according to claim 1 , wherein said method further comprises the step of: setting a frequency of said test pattern so that it can be lower than any data frequency of user data recorded in said plurality of tracks to be measured, wherein said test pattern is a single repeated pattern.
5. The RW offset setting method according to claim 1 , wherein said method further comprises the step of: finding an amplitude from an amplification degree in A/D converting means for an analog signal read from said disk recording medium by said read head.
6. A read data error recovery method for recovering a read data error of recorded data in a disk device including a rotary actuator having a head section for accessing a disk recording medium, comprising the steps of: A determining an off-track direction where an amplitude increases, by moving said head section to off-track positions on both sides of an on-track nominal position and measuring an amplitude of read back signals by a read head in the limited vicinity of a data sector where a read data error occurs; B searching an off-track position where said amplitude becomes a local maximum by gradually shifting said head section in the off-track direction where said amplitude increases and measuring said amplitude at each off-track position; and C reading data recorded in said data sector by moving said head section to the off-track position where said amplitude becomes a local maximum.
7. The read data error recovery method according to claim 6 , said method further comprising the step of: executing the steps A to C if said read data error is not recovered even if data recovery at an on-track position is performed.
8. The read data error recovery method according to claim 6 , wherein said method further comprises the step of: finding said amplitude from an amplification degree in A/D converting means for an analog read signal by the read head.
9. A read data error recovery method for recovering a read data error of recorded data in a disk device with a rotary actuator having a head section for accessing a disk recording medium, said method comprising the steps of: A performing tracking with said head section at a plurality of different tracking positions in a predetermined search range with regard to a track where said read data error occurs and measuring respective amplitudes of read head signals by the head section in the vicinity of a data sector where the read data error occurs; B finding an approximate expression of a profile of the measured amplitude for each of the plurality of tracking positions and finding a position, where a maximum value is given in said approximate expression, as a tracking position where amplitude of the read back signal reaches a maximum value; C tracking to a position with said head section where the amplitude maximizes; and D reading data recorded in the data sector.
10. The read data error recovery method according to claim 9 , wherein said method further comprises the step of: executing said steps A to D after said read data error is not recovered and said data track position is lost even if data recovery at a predetermined off-track position read steps are performed, in general error recovery procedure.
11. The read data error recovery method according to claim 9 , wherein said method further comprises the step of: finding a search range, wherein said search range is a range of a part of a track where said read data error occurs, or an entire range of the track where said read data error occurs, or an entire range of the track where said read data error occurs and a range of a part of tracks adjacent to this track.
12. The read data error recovery method according to claim 9 , wherein said method further comprises the step of: finding an amplitude from an amplification degree in A/D converting means for an analog read signal read from said disk recording medium by a read head.
13. A disk device comprising: a disk recording medium having a plurality of sectored tracks in which data are recorded; a head section including a write head and a read head for accessing data recorded on said disk recording medium; a rotary actuator for moving said head section in a radial direction of said disk recording medium; and a control unit for controlling said rotary actuator, said control unit including means for recovering a read data error of recorded data, said means for recovering including: means for determining an off-track direction where an amplitude increases, by moving said head section to off-track positions on both sides of an on-track nominal position and measuring an amplitude of read back signals by a read head in the limited vicinity of a data sector where a read data error occurs; means for searching an off-track position where said amplitude becomes a local maximum by gradually shifting said head section in the off-track direction where said amplitude increases and measuring said amplitude at each off-track position; and means for reading data recorded in said data sector by moving said head section to the off-track position where said amplitude becomes a local maximum.
14. A disk device comprising: a disk recording medium having a plurality of sectored tracks in which data are recorded; a head section for accessing data recorded on said disk recording medium; a rotary actuator for moving said head section in a radial direction of said disk recording medium; and a control unit for controlling disk access by said head section, said control unit including means for recovering a read data error of recorded data, said means for recovering including: means for performing tracking with said head section at a plurality of different tracking positions within a predetermined search range of a track where said read data error occurs and measuring respective amplitudes of read head signals by the head section in the vicinity of a data sector where the read data error occurs; finding an approximate expression of a profile of the measured amplitude for each of the plurality of tracking positions and finding a position, where a maximum value is given in said approximate expression as a tracking position where amplitude of the read back signal reaches a maximum value; tracking to a position with said head section where the amplitude maximizes; and reading data recorded in the data sector.
15. A disk device, comprising: a disk recording medium having a plurality of sectored tracks in which data are recorded; a head section including a write head and a read head for accessing said disk recording medium; a rotary actuator for moving said head section in a radial direction of said disk recording medium; and a control unit for controlling disk access by said head section, said control unit including means for configuring said disk drive to compensate for a RW offset between the write head and the read head, said means for configuring including: means for recording a test pattern utilizing said write head in each of a plurality of tracks of said disk recording medium; means for reading said test patterns utilizing said read head at a plurality of different tracking positions for each of the plurality of tracks, and measuring an amplitude of a read back signal at each tracking position; means for finding an approximate expression of a profile of the measured amplitude at each of said plurality of tracking positions for each of said plurality of tracks to be measured; means for finding a tracking position that gives a maximum value of said approximate expression of each of said plurality of tracks to be measured; means for determining, based upon the tracking position found for each measured track, a plurality of coefficients of a track-dependent arithmetic expression by which a RW offset for any track in said disk device can be calculated; and means for storing said plurality of coefficients within said disk device.
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February 23, 2001
November 18, 2003
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